The present invention relates to a monolithic switching matrix operating in the ultra-high frequency range. All the intersection points of the matrix are identical and are produced with active components, particularly field effect transistors having a gain making it possible to compensate or balance the losses at each switching node or junction.
Ultra-high frequency switching matrixes are used in telecommunications for switching the paths of the beam without any demodulation thereof in base bands. They are produced with passive division-combination couplers using tuned microstrips and the controllable switches are PIN diodes or field effect transistors. The system has a hybrid structure and consequently occupy a larger volume and surface than in integrated circuitry. Moreover, in a switching matrix with passive elements which consequently do not have an inherent gain, the intersection points are all different as a function of their position in the matrix, because it is necessary to take account of losses of each coupler, so that the coupling differs at each point and therefore so do the couplers.
Monolithic technology is completely suitable for producing switching matrixes and it is able to bring about a volume and heat dissipation gain. Two basic elements are used, namely PIN diodes and field effect transistors. These two elements correspond to two different structures, in which the monolithic integrated circuits provide original and interesting solutions for the industrialization of very high frequency telecommunications.
The switching matrix according to the invention is monolithic and uses active components whose gain makes it possible to balance the switched signals independently of the switching losses, in the manner stated hereinbefore. It has the advantage that all the switching points are identical, which facilitates the construction of an integrated circuit. In the switching matrix according to the invention, a signal from a first path or channel is divided by a first system or divider using at least one bi-drain or bi-source field effect transistor or two parallel field effect transistors. The passage of this signal to a second path or channel is controlled by a bi-gate field effect transistor or two field effect transistors in series, or by a PIN diode. The coupling of the signal from the first channel with the second channel is obtained by a second system or combiner, which can be identical to the switching system, i.e. a multi-gate transistor or several transistors in series. In the monolithic integrated circuit, the intersection of the paths of the switching matrix, in the form of metal lines on the surface of the substrate of the integrated circuit pellet, is made possible by the known techniques of a bridge insulated by a dielectric layer, or by an air bridge, the two paths intersecting in the air, or by multi-level shielding, the two paths intersecting in the semiconductor material, or passing from a first to a second face of the integrated circuit pellet by means of metallized holes.
All the means used for realizing a switching matrix according to the invention are consequently homogeneous, because they are integrated circuits and the field effect transistors and conductive metallizations, optionally PIN diodes, are realized on the same semiconductor material pellet. This represents a significant advantage compared with known switching matrixes, which are produced by hybrid techniques and microstrips on beryllium oxide or alumina substrates.